Some bacteria are known to have probiotic properties, i.e. they have a beneficial health effect on the host when ingested in adequate viable amounts. Particularly, bacterial strains belonging to the genera Lactobacillus and Bifidobacterium have been the subject of many studies demonstrating preventive clinical effects in various fields and on certain physiological functions. These probiotics are generally safe and notably capable of promoting proper operation of the intestinal flora. Besides clear evidence that it has positive effects on the health of the consumer, for a bacterium to fulfil the probiotic definition, it has to be able to survive in and colonize the intestines and survive the harsh processes at production and storage of the food. The clinical evidence indicates that the daily dose of probiotic bacteria should be at least 109 CFU to ensure probiotic efficacy.
The market for probiotic products continues to grow. Probiotics have especially been implemented in dairy products wherein the lactic acid bacteria are relatively well-adapted to the medium. Now orange juices as well as other types of fruit juices and beverages containing pureed fruit and fruit juice have been identified as important vehicles of probiotic cultures which have the benefits of both fruits and probiotics. Additionally, fruit beverages, which contain no milk components, are excellent ways of administration of hypoallergenic probiotics, such as L. casei 431® (Chr. Hansen, Hoersholm, Denmark).
However, the rather acidic environment of fruit juices causes a large initial cell count reduction when a reference probiotic bulk is added to e.g. an orange juice. For successful application of probiotic cultures in fruit beverages, appropriate concentrations of probiotic cells have to be ensured during shelf life. Thus, increasing the survival of probiotic cultures in orange juice and other fruit beverages is regarded as very critical.
Methods for producing a fruit beverage containing efficient amounts of live Lactobacilli are known in the art, such as in European Patent EP 0113055, which is related to a method comprising bringing a fruit juice into contact with a solid agent to remove the bacteriostatic components and then proliferating lactobacillus in the fruit juice at a pH of 4.0 or lower.
However, in such fruit beverages it is possible to observe bacterial growth and/or activity which induce a production of gas and off-flavor which makes them unsuitable for consumption.
US Patent Application US 2010/0086646 relates to fresh plant juice and/or milk-based food product comprising live probiotics and a dietary protonated weak monoacid with a pH between 3 and 4, the latter prevented probiotics from producing false taste and/or gas in the food product.
PCT Patent Application WO 2010/132017 is directed to a probiotic fruit juice drink comprising at least one strain of probiotic bacteria and at least one gas formation reducer chosen from acerola, pomegranate, cranberry, arqnia, blackcurrant, buckthorn or elderberry.
The addition of monoacids may affect the organoleptic properties of the food product and has also been seen to affect negatively the survival rate of the probiotic bacteria. The addition of acid formation reducers also seems to negatively affect the survival rate of probiotic bacteria. Addition of agents for removal of bacteriostatic compounds and/or for reducing false taste and/or gas in the food product may furthermore prove to be costly.
Thus, there remains a need within the technical field to provide alternative methods for producing probiotic fruit beverages with a high probiotic value, wherein the probiotic fruit beverage exhibits a good taste without off-flavor and gas production, and wherein the probiotic fruit beverage has a long shelf-life. Especially, there is a need for methods which do not involve the addition of solid agents, monoacids or other compounds which may affect the organoleptic qualities of the fruit beverage.
The present invention proposes an alternative method of producing a fruit beverage comprising probiotic bacteria which have been acid-adapted prior to inoculation into the fruit beverage.